package com.ctrw.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.ctrw.dto.Result;
import com.ctrw.entity.Shop;
import com.ctrw.entity.ShopType;
import com.ctrw.entity.User;
import com.ctrw.mapper.ShopMapper;
import com.ctrw.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.ctrw.utils.CacheClient;
import com.ctrw.utils.RedisConstants;
import com.ctrw.utils.RedisData;
import com.ctrw.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.ctrw.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    StringRedisTemplate stringRedisTemplate;

    @Resource
    CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //防止缓存穿透的代码
        //方法一
        //Shop shop = queryWithPassThrough(id);
        //方法二：调用封装好的redis工具 this::getById 是 id2 -> getById(id2) 的简写
        //Shop shop = cacheClient.
        //        queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, id2 -> getById(id2), CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        Shop shop = cacheClient.
//                queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //使用互斥锁防止缓存击穿的代码
        //Shop shop = queryWithMutex(id);
        //使用逻辑过期的代码
        //Shop shop = queryWithLogicalExpire(id);
        Shop shop = cacheClient.
                queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return Result.ok(shop);
    }

    private Shop queryWithMutex(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1、从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3、存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        // 判断命中的是否是空值
        if (shopJson != null) {
            return null;
        }
        //4、实现缓存重建
        //4.1、获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2、判断是否获取锁
            if (!isLock) {
                //4.3、失败，则休眠重试
                Thread.sleep(50);
                //递归调用本函数
                return queryWithMutex(id);
            }

            //4.4、成功，根据id查询数据库
            shop = getById(id);
            //5、如果数据库中不存在，返回错误，且给redis写入null防止缓存穿透
            if (shop == null) {
                stringRedisTemplate.opsForValue().set(key, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6、存在，写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7、释放互斥锁
            unlock(lockKey);
        }
        //8、返回
        return shop;
    }

//    //使用给缓存写入空值，防止缓存穿透的代码
//    private Shop queryWithPassThrough(Long id) {
//        String key = CACHE_SHOP_KEY + id;
//        //1、从redis查询商铺缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        //2、判断是否存在
//        if (StrUtil.isNotBlank(shopJson)) {
//            //3、存在，直接返回
//            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
//            return shop;
//        }
//        // 判断命中的是否是空值
//        if (shopJson != null) {
//            return null;
//        }
//        //4、缓存中不存在，根据id查询数据库
//        Shop shop = getById(id);
//        //5、如果数据库中不存在，返回错误，且给redis写入null防止缓存穿透
//        if (shop == null) {
//            stringRedisTemplate.opsForValue().set(key, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
//            return null;
//        }
//        //6、存在，写入redis
//        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        //7、返回
//        return shop;
//    }

//    //自定义线程池
//    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
//
//    private Shop queryWithLogicalExpire(Long id) {
//        String key = CACHE_SHOP_KEY + id;
//        //1、从redis查询商铺缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        //2、判断是否存在
//        if (StrUtil.isBlank(shopJson)) {
//            //3、不存在，直接返回空
//            return null;
//        }
//        //4、命中，先把json反序列化为对象
//        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
//        JSONObject data = (JSONObject) redisData.getData();
//        Shop shop = JSONUtil.toBean(data, Shop.class);
//        LocalDateTime expireTime = redisData.getExpireTime();
//        //5、判断是否过期
//        if (expireTime.isAfter(LocalDateTime.now())) {
//            //5.1、未过期，直接返回商铺信息
//            return shop;
//        }
//        //5.2、已过期需要缓存重建
//        //6、缓存重建
//        //6.1、获取互斥锁
//        String lockKey = LOCK_SHOP_KEY + id;
//        boolean isLock = tryLock(lockKey);
//        //6.2、判断是否获得锁
//        if (isLock) {
//            //6.3、成功，开启独立线程，实现缓存重建
//            CACHE_REBUILD_EXECUTOR.submit(() -> {
//                try {
//                    //重建缓存
//                    this.saveShop2Redis(id, 30L);
//                } catch (Exception e) {
//                    throw new RuntimeException(e);
//                } finally {
//                    //释放锁
//                    unlock(lockKey);
//                }
//            });
//        }
//        //6.4、返回过期的商铺信息
//        return shop;
//    }

    //redis实现的互斥锁上锁
    private boolean tryLock(String key) {
        Boolean b = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(b);
    }
    //解锁
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) return Result.fail("店铺id不能为空");
        //1、更新数据库
        updateById(shop);
        //2、删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1、判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2、计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        // 3、查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4、解析出id
        if (results == null) {
            return Result.ok();
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            //没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 截取from ~ end 的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            //获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5、根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD( id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6、返回
        return Result.ok(shops);
    }

    //向redis中提前写入数据并设置逻辑过期时间
    public void saveShop2Redis(Long id, Long expireSeconds) {
        //1、查询店铺数据
        Shop shop = getById(id);
        //2、封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3、写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,
                JSONUtil.toJsonStr(redisData));
    }
}
